tree-equal (Function)

Syntax:

Arguments and Values:

tree-1—a tree.

tree-2—a tree.

test—a designator for a function of two arguments that returns a generalized boolean.

test-not—a designator for a function of two arguments that returns a generalized boolean.

generalized-boolean—a generalized boolean.

Description:

tree-equal tests whether two trees are of the same shape and have the same leaves. tree-equal returns true if tree-1 and tree-2 are both atoms and satisfy the test, or if they are both conses and the car of tree-1 is tree-equal to the car of tree-2 and the cdr of tree-1 is tree-equal to the cdr of tree-2. Otherwise, tree-equal returns false.

tree-equal recursively compares conses but not any other objects that have components.

The first argument to the :test or :test-not function is tree-1 or a car or cdr of tree-1; the second argument is tree-2 or a car or cdr of tree-2.

Examples:

 (setq tree1 '(1 (1 2))
       tree2 '(1 (1 2))) → (1 (1 2))
 (tree-equal tree1 tree2) → true
 (eql tree1 tree2) → false
 (setq tree1 '('a ('b 'c))
       tree2 '('a ('b 'c))) → ('a ('b 'c))
→ ((QUOTE A) ((QUOTE B) (QUOTE C)))
 (tree-equal tree1 tree2 :test 'eq) → true

Exceptional Situations:

The consequences are undefined if both tree-1 and tree-2 are circular.

See Also:

equal, Section 3.6 (Traversal Rules and Side Effects)

Notes:

The :test-not parameter is deprecated.